This invention relates to disposable razors, and particularly to a visual means for readily indicating to the user the relative amount of wear that the blade of a given disposable razor has undergone.
Disposable razors have seemingly become increasingly popular because of their ease of use and the lack of required care and maintenance. Generally, disposable razors comprise a plastic handle and a frame or head, in which frame or head one or more shaving blades are mounted. Alternatively, for purposes of this application, the term "disposable razor" is also intended to include a razor blade mounted in a "cartridge," for fitting into a non-disposable handle, the cartridge itself being disposable.
The blade edge of a disposable razor gradually wears down with use, until at some point the user decides to discard the razor. For each individual shaver, the number of shaves that he or she will enjoy from a particular razor is to some extent a matter of individual choice. An individual will make a subjective judgment--based upon how the blade feels on the skin during the shaving stroke, or perhaps on other grounds--that it is time to dispose of that particular razor and begin to use a new one. Visual inspection of the blade edge itself usually yields little or no information as to how worn the blade has become.
It is believed that the typical user of a disposable razor would benefit from the inclusion of some reliable, and easily recognizable, visual indicator of the relative amount of wear that a particular disposable razor blade has undergone. With such a visual indication, it would not be necessary to determine the wear on the razor by the amount of pain or discomfort felt when the blade was used.
In this connection, it has been suggested in Hensel U.S. Pat. No. 2,703,451, to provide a so-called "tell-tale" marking on a razor blade itself, which marking will be worn away during use of the blade, thereby "telling" the user how much the blade has been used. However, since during shaving only the very edge of the blade contacts the skin area and the hair being shaved, the "tell-tale" marking of the Hensel patent is of little practical use--only the small portion of the marking at the edge of the blade will be worn away, and changes to that small portion may not be readily recognizable. Furthermore, placement of the "tell-tale" marking on the blade itself may interfere with the shaving action of the blade edge.
Griffiths U.S. Pat. No. 3,879,844 suggests the use of an "indicator mark" on the frame of a blade cartridge (or on the blade itself) to indicate whether the blade has been used or whether it is still new. However, that patent does not disclose or suggest that the "indicator mark" be used to indicate the relative amount of wear on the blade, but only whether the blade has been used at all.
Booth U.S. Pat. No. 4,170,821 discloses a "shaving aid"--such as a lubricant, whisker softener, razor cleaner, medicinal agent, and/or cosmetic agent--in the form of a water-soluble resin affixed to the frame or cartridge of a disposable razor blade adjacent the shaving edge. Upon wetting and stroking of the razor blade over the skin, the shaving aid is applied to the skin. However, nothing in Booth suggests that this "shaving aid" serve any function to indicate the relative wear on the blade.